Forced exercise increases muscle mass in EAE despite early onset of disability

Effectiveness of exercise interventions in animal models of multiple sclerosis

Multiple sclerosis (MS) is associated with an impaired immune system that severely affects the spinal cord and brain, and which is marked by progressive inflammatory demyelination. Patients with MS may benefit from exercise training as a suggested course of treatment. The most commonly used animal models of studies on MS are experimental autoimmune/allergic encephalomyelitis (EAE) models. The present review intends to concisely discuss the interventions using EAE models to understand the effectiveness of exercise as treatment for MS patients and thereby provide clear perspective for future research and MS management. For the present literature review, relevant published articles on EAE animal models that reported the impacts of exercise on MS, were extracted from various databases. Existing literature support the concept that an exercise regimen can reduce the severity of some of the clinical manifestations of EAE, including neurological signs, motor function, pain, and cognitive deficits. Further results demonstrate the mechanisms of EAE suppression with information relating to the immune system, demyelination, regeneration, and exercise in EAE. The role for neurotrophic factors has also been investigated. Analyzing the existing reports, this literature review infers that EAE is a suitable animal model that can help researchers develop further understanding and treatments for MS. Besides, findings from previous animal studies supports the contention that exercise assists in ameliorating MS progression.

Physical exercise therapy for autoimmune neuroinflammation: Application of knowledge from animal models to patient care

Physical exercise (PE) impacts various autoimmune diseases. Accordingly, clinical trials demonstrated the safety of PE in multiple sclerosis (MS) patients and indicated beneficial outcomes. There is also an increasing body of research on the beneficial effects of exercise on experimental autoimmune encephalomyelitis (EAE), the animal model of MS, and various mechanisms underlying these effects were suggested. However, despite the documented favorable impact of PE on our health, we still lack a thorough understanding of its effects on autoimmune neuroinflammation and specific guidelines of PE therapy for MS patients are lacking. To that end, current findings on the impact of PE on autoimmune neuroinflammation, both in human MS and animal models are reviewed. The concept of personalized PE therapy for autoimmune neuroinflammation is discussed, and future research for providing biological rationale for clinical trials to pave the road for precise PE therapy in MS patients is described.

Biological Aspects of Selected Myokines in Skeletal Muscle: Focus on Aging

In the last decade, clear evidence has emerged that the cellular components of skeletal muscle are important sites for the release of proteins and peptides called "myokines", suggesting that skeletal muscle plays the role of a secretory organ. After their secretion by muscles, these factors serve many biological functions, including the exertion of complex autocrine, paracrine and/or endocrine effects. In sum, myokines affect complex multi-organ processes, such as skeletal muscle trophism, metabolism, angiogenesis and immunological response to different physiological (physical activity, aging, etc.) or pathological states (cachexia, dysmetabolic conditions, chronic inflammation, etc.). The aim of this review is to describe in detail a number of myokines that are, to varying degrees, involved in skeletal muscle aging processes and belong to the group of proteins present in the functional environment surrounding the muscle cell known as the "Niche". The particular myokines described are those that, acting both from within the cell and in an autocrine manner, have a defined relationship with the modulation of oxidative stress in muscle cells (mature or stem) involved in the regulatory (metabolic or regenerative) processes of muscle aging. Myostatin, IGF-1, NGF, S100 and irisin are examples of specific myokines that have peculiar features in their mechanisms of action. In particular, the potential role of one of the most recently characterized myokines-irisin, directly linked to an active lifestyle-in reducing if not reversing senescence-induced oxidative damage is discussed in terms of its possible application as an agent able to counteract the deleterious effects of muscle aging.

Exercise preserves muscle mass and force in a prostate cancer mouse model

The purpose of this study was to examine the effects of exercise in modulating biomarkers of sarcopenia in a treatment naïve transgenic adenocardinoma of the mouse prostate (TRAMP) model. Thirty TRAMP mice were randomized to either exercise (voluntary wheel running) or no-treatment control group for a period of 20 weeks. During necropsy, gastrocnemius muscles and prostate tumors were harvested and weighed. Gastrocnemius concentrations of myostatin, insulin-like growth factor (IGF)-1 and tumor necrosis factor (TNF)-α were quantified. Exercise mice had greater muscle mass than controls (p=0.04). Myostatin was significantly lower in the exercise group compared to controls (p=0.01). Exercise mice maintained forelimb grip force while control mice had a significaint decrease (p=0.01). No significant difference was observed in pre-post all limb grip strength. Further, forelimb and all limb grip strength was negatively associated with tumor mass (p<0.01).

Exercise intensity-dependent immunomodulatory effects on encephalomyelitis

Background

Exercise training (ET) has beneficial effects on multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). However, the intensity‐dependent effects of ET on the systemic immune system in EAE remain undefined.

Objective

(1) To compare the systemic immune modulatory effects of moderate versus high‐intensity ET protocols in protecting against development of EAE; (2) To investigate whether ET affects autoimmunity selectively, or causes general immunosuppression.

Methods

Healthy mice performed moderate or high‐intensity treadmill running programs. Proteolipid protein (PLP)‐induced transfer EAE was utilized to examine ET effects specifically on the systemic immune system. Lymph node (LN)‐T cells from trained versus sedentary donor mice were transferred to naïve recipients and EAE severity was assessed, by clinical assessment and histopathological analysis. LN‐T cells derived from donor trained versus sedentary PLP‐immunized mice were analyzed in vitro for proliferation assays by flow cytometry analysis and cytokine and chemokine receptor gene expression using real‐time PCR. T cell‐dependent immune responses of trained versus sedentary mice to the nonautoantigen ovalbumin and susceptibility to Escherichia coli‐induced acute peritonitis were examined.

Results

High‐intensity training in healthy donor mice induced significantly greater inhibition than moderate‐intensity training on proliferation and generation of encephalitogenic T cells in response to PLP‐immunization, and on EAE severity upon their transfer into recipient mice. High‐intensity training also inhibited LN‐T cell proliferation in response to ovalbumin immunization. E. coli bacterial counts and dissemination were not affected by training.

Interpretation

High‐intensity training induces superior effects in preventing autoimmunity in EAE, but does not alter immune responses to E. coli infection.

Regular Exercise Modifies Histopathological Outcomes of Pharmacological Treatment in Experimental Autoimmune Encephalomyelitis

Background: Although it has been suggested that healthier lifestyle may optimize effects of the immunomodulation drugs for treating multiple sclerosis (MS), the knowledge regarding this kind of interactions is limited.

Objective: The aim of the present study was to investigate the effects of treadmill exercise in combination with pharmacological treatment in an animal model for MS.

Methods: C57BL/6J female mice were subjected to daily treadmill exercise for 4 weeks before immunization and 6 weeks before clinical presentation of disease. Dimethyl fumarate (DMF) or glatiramer acetate (GA) were administered after the first clinical relapse. Histopathological analyses were carried out in the lumbar spinal cord at peak disease and at 1 or 14 days post-treatment (dpt).

Results: Exercised-GA treated animals demonstrated decreased astrocytic response in the spinal dorsal horn with an improvement in the paw print pressure. Exercised-DMF treated animals showed an increased microglial/macrophage response on both ventral and dorsal horn that were associated with clinical improvement and synaptic motoneuron inputs density.

Conclusion: The present data suggest that prior regular exercise can modify the effects of pharmacological treatment administered after the first relapse in a murine model for MS.

The Effects of Aerobic Exercise on the Recovery of Walking Ability and Neuroplasticity in People with Multiple Sclerosis: A Systematic Review of Animal and Clinical Studies

INTRODUCTION

Walking is of high priority for people with multiple sclerosis (PwMS). It remains unclear whether aerobic exercise can improve walking ability and upregulate neurotrophins. This review aims to consolidate evidence to develop optimal aerobic training parameters to enhance walking outcomes and neuroplasticity in PwMS.

METHODS

Clinical studies examining aerobic exercise for ≥3 weeks, having outcomes on walking with or without neurotrophic markers, were included. Studies utilizing animal models of MS were included if they employed aerobic exercise with outcomes on neurological recovery and neurotrophins. From a total of 1783 articles, 12 clinical and 5 animal studies were included.

RESULTS

Eleven clinical studies reported improvements in walking ability. Only two clinical studies evaluated both walking and neurotrophins, and neither found an increase in neurotrophins despite improvements in walking. Patients with significant walking impairments were underrepresented. Long-term follow-up revealed mixed results. Two animal studies reported a positive change in both neurological recovery and neurotrophins.

CONCLUSION

Aerobic exercise improves walking ability in PwMS. Gains are not consistently maintained at 2- to 9-month follow-up. Studies examining levels of neurotrophins are inconclusive, necessitating further research. Aerobic exercise enhances both neurological recovery and neurotrophins in animal studies when started 2 weeks before induction of MS.

Comprehensive catwalk gait analysis in a chronic model of multiple sclerosis subjected to treadmill exercise training

BACKGROUND

Multiple sclerosis (MS) is a demyelinating disease with a wide range of symptoms including walking impairment and neuropathic pain mainly represented by mechanical allodynia. Noteworthy, exercise preconditioning may affect both walking impairment and mechanical allodynia. Most of MS symptoms can be reproduced in the animal model named experimental autoimmune encephalomyelitis (EAE). Usually, neurological deficits of EAE are recorded using a clinical scale based on the development of disease severity that characterizes tail and limb paralysis. Following paralysis recovery, subtle motor alterations and even mechanical allodynia investigation are difficult to record, representing sequels of peak disease. The aim of the present study was to investigate the walking dysfunction by the catwalk system (CT) in exercised and non-exercised C57BL/6 mice submitted to EAE with MOG35-55 up to 42 days post-induction (dpi).

METHODS

Twenty-four C57BL/6 female mice were randomly assigned to unexercised (n = 12) or exercised (n = 12) groups. The MOG35-55 induced EAE model has been performed at the beginning of the fifth week of the physical exercise training protocol. In order to characterize the gait parameters, we used the CT system software version XT 10.1 (Noldus Inc., The Netherlands) from a basal time point (before induction) to 42 days post induction (dpi). Statistical analyses were performed with GraphPad Prisma 4.0 software.

RESULTS

Data show dynamic gait changes in EAE mice including differential front (FP) and hind paw (HP) contact latency. Such findings are hypothesized as related to an attempt to maintain balance and posture similar to what has been observed in patients with MS. Importantly, pre-exercised mice show differences in the mentioned gait compensation, particularly at the propulsion sub-phase of HP stand. Besides, we observed reduced intensity of the paw prints as well as reduced print area in EAE subjects, suggestive of a development of chronic mechanical allodynia in spite of being previously exercised.

CONCLUSIONS

Our data suggest that Catwalk system is a useful tool to investigate subtle motor impairment and mechanical allodynia at chronic time points of the EAE model, improving the functional investigation of gait abnormalities and demyelination sequelae.